Flashlamp and apparatus for making same

ABSTRACT

A flashlamp having a small bulb volume (preferably less than 1 cc.) contains a filling of metal foil shreds, preferably of zirconium, of small cross section of 2 to 10 X 10 4 mm.2, which have from 8 to 50 sharp bends, forming acute angles, preferably from 12 to 30 bends per 100 mm. of shred length to effect point contact between the filling and bulb wall. The radius of curvature of the bends is preferably smaller than 0.3 mm. and the angle formed by an individual bend is preferably smaller than 60*. The cross section of the ball formed by a shred of 100 mm. in length is from 40 to 8 mm.2, preferably from 30 to 12 mm.2. A light gain exceeding 40 percent and a longer peak time is obtained.

O v United States Patent [72] Inventors Peterllauhnann [56] RelerencesCited Sdln; UNrTED sTATEs PATENTS ggdlimmmmn'nm 2,162,841 6/1939 Korver 431/95 2l A IN N875 3,045,460 7/1962 amuse eral. 431/95 [22] F.1lpd'- M ,u 1970 3,158,014 11/1964 arouse 431/95 {45} femm 1);"281971 3,228,216 1/1966 Desauinierseral 431/95 [73] Assignee Patent-Treuhand-Gesellschnh,tur Primary Examiner-Edward J. Michael elektrische Gluhhmpen mb Attorney-Flynn & Frishauf Munlch,Germany 1,1969 Pnomy lx-mim ABSTRACT: A flashlamp having a small bulb volume [3l] P19 134173 (preferably less than l cc.) contains a filling of metal foil [54] FLASHLAMP AND APPARATUS FOR MAKING shreds, preferably of zirconium, of small cross section of 2 to l0 X l0 mm?, which have from 8 to 50 sharp bends, forming acute angles, preferably from l2 to 30 bends per lOO mm. of shred length to effect point contact between the filling and bulb wall. The radius of curvature of the bends is preferably smaller than 0.3 mm. and the angle formed by an individual bend is preferably smaller than 60. The cross section of the ball formed by a shred of 100 mm. in length is from 40 to 8 mm?, preferably from 30 to l2 mm?. A light gain exceeding 40 percent and a longer peak time is obtained.

l l g 1 ,1 1: 2 i 1.

PATENTE() [15u28 um SHEET 1 UF 3 FIG.1

FIG.

Peter Kaufmann Reinhold Liepert INVENTORS U Bv 'YTAT ToRNEvs PATENTEUEECZBIQH 3,630,550 snm a uf 3 Pfr- Kaufmann j Reinhold Lieperi INVENTORS PMENYEU m28 :an

SHEET 3 UF 3 IIIJ AIRF LOW approx. 2-3 atm.

FIG.5

AIR FLOW approx. 3atm.

INVENTORS FLASI-ILAMP AND APPARATUS FOR MAKING SAME This invention relates to flashlamps, and more particularly to f'lashlamps for photographic uses having a bulb of small volume, preferably below l cc., which contains combustible material of filamentary, twisted or crumpled shreds of metal foil therein.

Lamps of this type are required to give off a large quantity of light in a short period of time. The period of time between application of the ignition voltage and attainment of the peak value of light output, the so-called peak time, should be in the range of about I3 msec. in compliance with international conventions. This requirement imposes special restriction with respect to the quantity of the combustion-supporting medium (generally oxygen) and the type of combustible material within the bulb of the lamp. i

It is well known to vcut narrow shreds of combustible foil off of a broad ribbon of foil by means of a rotary shaft having transverse cutting edges. The shreds are then pneumatically sucked into the interior of the bulb through a feed conduit, crumpled by impinging on the bulb wall, and distributed within the bulb by the airflow as described for example, in U.S. Pat. No. 2,347,046. It is also known to provide a chamber in the suction conduit wherein the foil shreds are caused to impinge repeatedly on the wall of the chamber, thereby crumpling the foil shreds (see U.S. Pat. No. 3,120,694).

In the known flashlamps the combustible material extends within the bulb and on the bulb wall in relatively large, arbitrarily shaped loops. In these flashlamps, the peak time (that is, the time until attainment of the peak light value) is generally considerably below the generally fixed time of 13 msec. This is mainly true for bulbs of small volume and highfill pressure.

The main object of the present invention is to provide a flashlamp having improved performance and having a llonger peak time with a given amount of combustible material.

SUMMARY OF THE INVENTION According to the invention a flashlamp comprising a bulb of small volume, preferably below l cc.; contains combustible material of filamentary, twisted or crumpled shreds of metal foil which is sharply bent, such as by buckling. Each foil has from eight to 50 bends and preferably from 12 to 30 bends per 100 mm. of length of the foil shreds. The foil shreds have a cross-sectional area of from 2 to 10X104 mm.2 The sharply bent shreds thereby form a ball with a cross-sectional area of from 40 to 8 mm?, and preferably from 30 to l2 mm.2 per 100 mm. of shred length. The sharp bends in the foil shreds have a radius of curvature substantially smaller than 0.3 mm. and the formed angle of an individual bend in generally less than 60 in a preferred case.

Apart from the surprising lengthening of the peak time (that is, lengthening of time until attainment of the peak value), in spite of the use of the same quantity of material in the bulb, by the repeated sharp bending through a comparatively small angle, the deformation of the foil shreds according to the present invention has the further advantage that with a uniform distribution within the bulb, the bearing area of the combustible material on the inner surface of the bulb wall is small. 1n the prior art flashlamps large portions of the loops of combustible material are linearly abutting the bulb wall whereas in the present invention the contact of the sharply bent foil shreds with the bulb wall is more punctiform. This point contact with the bulb wall apparently promotes optimum combustion without energy losses due to extensive heat transmission to the glass, and effects also an increase in the quantity of light produced.

The fixing of another rated value for the peak time would entail a variation of the number of sharp bends in accordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a fIashlamp according to the present invention;

FIG. 2 is an enlarged sectional view of a portion of a prior art fiashlamp with a conventional foil filling;

FIG. 3 is an enlarged sectional view of a portion of a flashlamp with a foil filling according to the present invention;

FIGS. 4a-4c show various illustrations of the ball formation as a function of the number of sharp bends for a foil shred; and

FIG. 5 illustrates a device for fabricating the sharply bent foil shreds when producing a lamp according to the present invention.

The lamp illustrated in FIG. l comprises a tubular bulb l having an outer diameter of 6.3 mm., an internal length of l5 mm., and a volume of 0.2 cc., the bulb l being coated with a varnish coat 2 as a protection from shattering. The filling 3 comprises 14 mg. of zirconium in the form of foil shreds 4 having a length of mm., a width of 32 y., and a thickness of 20 p.. Each individual foil shred 4 has about 27 sharp bends therein, the radius of curvature of each individual bend being smaller than 0.3 mm., and the formed angle for each bend being less than 60. Each of the bent shreds 4 forms substantially a ball, each ball having a cross-sectional area of approximately l5 mm.2 The lamp is filled with oxygen at a pressure of 18 atm. The f'lashlamp uses conventional ignition means 5, and conventional leads 6 and 7 coupled to the ignition means 5.

FIG. 2 shows in the prior art flashlamps, the relatively large loops of shredded foil filling 4 which often linearly abut the bulb wall l. FIG. 3, on the other hand, shows the sharply bent structure of foil shreds 4 according to the present invention and their substantially punctiform contact with the bulb wall 1.

FIGS. 4a-c illustrate respectively individual foil shreds in the hitherto conventional form, shreds of the present invention with 13 bends and shreds of the present invention with 28 sharp bends. The conventionally bent foil shreds of FIG. 4a are distributed in loops over a large area. FIGS. 4b and 4c on the other hand, show the reduced cross sections-formed by means of increasing the number of sharp bends in the shreds which form the balls in accordance with the present invention.

FIG. 5 illustrates apparatus for producing the flashlamp of the present invention. As shown in FIG. 5, the foil shreds 4 supplied via tube 8 are sucked in by an airflow of about 3 atm. and are fed to a conduit such as tube 9. The foil shreds 4 are accelerated in tube 9 and flung against the wall of chamber l0. The shreds 4 are buckled by the impact against the wall of chamber 10 and are then flung by an airflow of from 2 to 3 atm. perpendicular to the original direction of flow against the wall of a second chamber l2 via acceleration conduit or tube Il to thereby form the final sharp bends. With the aid ofthe residual airflow the sharply bent shreds are passed through the conduit or tube 13 into the lamp bulb l which is mounted at the end of the tube 13. The lamp bulb is then evacuated and/or filled with the appropriate gases and is sealed off as is well known in the art (see for example, U.S. Pat Nos. 2,347,046 and 3,120,694).

In a lamp according to the embodiment of FIG. l having about 27 sharp bends per 100 mm. of shred length, the peak time is l2 msec. and the generated quantity of light 3,500 lumens. With a lamp filled with shreds having about 13 sharp bends per 100 mm. of shred length, the relative values are l0 msec. and 3,100 lumens. In the prior an lamps having conventional shred fillings, relative values of only 8 msec. and 2,500 lumens were attained. Thus, a light output gain of 40 percent is attained with lamps according to the present invention as compared with the known conventional lamps, without increasing the amount of combustible material within the bulb. Also the peak time is increased with the present invention.

We claim:

1. In a flashlamp comprising a bulb of small volume and combustible material of filamentary shreds of metal foil distributed therein;

the improvement wherein;

said foil shreds have a cross section area of from 2 to 10X10 '4 mm?, have from eight to S0 sharp bends per 100 mm. of length of a radius of curvature less than 0.3 mm., and a bend angle less than 60; and approximately form a ball with a cross-sectional area of from 40 to 8 mm?, per 100 mm. of shred length.

2. A flashlamp according to claim l wherein said foil shreds have from l2 to 30 sharp bends per 100 mm. of length and approximately form a ball with a cross-sectional area of from 30 to l2 mm.2 per 100 mm. of shred length.

3. A flashlamp according to claim 2, wherein the angle formed by an individual bend is substantially smaller than 60.

4. A flashlamp according to claim 1, wherein the angle 

2. A flashlamp according to claim 1 wherein said foil shreds have from 12 to 30 sharp bends per 100 mm. of length and approximately form a ball with a cross-sectional area of from 30 to 12 mm.2 per 100 mm. of shred length.
 3. A flashlamp according to claim 2, wherein the angle formed by an individual bend is substantially smaller than 60*.
 4. A flashlamp according to claim 1, wherein the angle formed by an individual bend is substantially smaller than 60*.
 5. A flashlamp according to claim 2 wherein the foil shreds are 100 mm. long, 32 Mu wide and 20 Mu thick.
 6. A flashlamp according to claim 1 wherein the foil shreds are 100 mm. long, 32 Mu wide and 20 Mu thick.
 7. A flashlamp according to claim 4 wherein the foil shreds are 100 mm. long, 32 Mu wide and 20 Mu thick.
 8. A flashlamp according to claim 2, wherein the foil shreds are composed of zirconium. 